1. Field of the Invention
This invention relates generally to a means for mounting automotive suspension struts so as to reduce operating friction within the strut.
2. Disclosure Information
Automotive suspension designs incorporating struts have taken a variety of forms. In the true MacPherson design, the strut is positioned between a wheel carrier, to which it is rigidly mounted, and the chassis, to which it is pivotally mounted. A coil spring is commonly mounted concentrically about the strut. In the "modified" MacPherson design, a spring mechanism is mounted between a lower control arm attached to the wheel carrier and the chassis. The strut is, nevertheless, rigidly fastened to the wheel carrier and pivotally mounted to the chassis at its upper end. The rigid mounting between the strut and the wheel carrier with both designs causes radially directed preloading of the strut pistion and bearing. This preloading is undesirable inasmuch as the static friction resulting therefrom increases the force necessary to initiate sliding of the pistion within the strut and therefore correspondingly increases the shock loading transmitted to the chassis of the vehicle when an obstruction is encountered on the roadway surface. Attempts to minimize this undesirable static friction have resulted in configurations wherein the spring is eccentrically mounted about the strut or the spring mounting pads are canted at an angle to the strut center line, as in U.S. Reissue Pat. No. 31,184. Although these solutions can result in a reduction of the strut friction, an undesirable effect may arise inasmuch as the packaging volume of the strut assembly may increase with either of the aforementioned structures.
The present invention is intended to effect a reduction of strut friction without causing an increase of the struts' package volume. A further object of the invention is the provision of a method for controllably reducing or modifying strut static friction characteristics. The present invention may be utilized with either MacPherson or modified MacPherson designs.